JPS6220525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-dimensional scanning device for writing or reading figures by two-dimensional scanning, and particularly to a two-dimensional scanning device that maintains a completely linear relationship between a signal and a scanning position and eliminates distortion. It performs a scan without any data.

Conventionally, in two-dimensional scanning devices,
Two-dimensional deflection devices such as those disclosed in Japanese Patent Application Laid-open No. 9321 or Japanese Patent Application Laid-Open No. 51-26050 are known. In either case, if the rotation angle range of the main deflection is constant with respect to the sub-deflection, the first
A distorted scan as shown in the figure is performed. In FIG. 1, main scanning is performed parallel to the X' axis, and sub scanning is performed in the Y' axis direction. To correct such a distorted scanning pattern, it is necessary to electrically correct the signal, which requires a position detector, a memory with a huge storage capacity, or an arithmetic circuit for correction.

An object of the present invention is to provide a two-dimensional scanning device that corrects scanning distortion by optical and mechanical means without using complicated electrical signal processing means as described above. . In other words, by suitably configured optical and mechanical means, the rotation angle range of the main deflection (X' direction) with respect to the secondary deflection (Y' direction) is constant, as shown in Figure 2. In this case, the input signal and the input signal are adjusted so that a distortion-free scanning figure is obtained, and the corresponding positional relationship on the scanning plane is at equal intervals for signals input at fixed time intervals. Ensure that a perfect linear relationship is maintained with the scan position.

To achieve the above object, in the present invention, the scanning lens has distortion characteristics corresponding to the characteristics of the main scanning deflection, and by rotating the scanning lens in accordance with the characteristics of the sub-scanning deflection, Eliminates distortion in the deflection direction and maintains a constant scanning speed in both the main and sub directions.
To obtain a scanned figure without distortion.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the basic configuration of the two-dimensional scanning device of the present invention. In FIG. 3, it is assumed that the incident parallel beams 1 are conditioned by the two-dimensional deflection mirror 2 so that the main scanning deflection plane of each incident beam 1 becomes a plane. In the case of FIG. 3, it is assumed that the incident beam 1 is incident parallel to the X-axis (in the illustrated example, the incident beam 1 is included in the X-axis). The two-dimensional deflection mirror 2
rotates for main scanning deflection around an axis Y _M that is always parallel to the mirror surface, and rotates for sub scanning deflection around an X axis that is perpendicular to the Y _M axis or parallel to the orthogonal axis. Assume that rotation is performed for the purpose of

In Figure 3, the sub-deflection for a rotation angle ω ₂ about the X-axis and the axis Y parallel to the deflection mirror surface.
Consider the case of principal deflection for rotation angle ω ₁ around _M. Assume that the Y _M axis is always within the Y-Z plane,
Although generality is not lost even if the origin 0 of the orthogonal coordinate system XYZ is not on the Y _M axis, here, to simplify the explanation, it is assumed that the origin 0 is on the Y _M axis. Third
As shown in the figure, when beam 1 is incident parallel to the X axis, the secondary deflection angle θ ₂ is ω ₂ and the main deflection angle θ ₁ is 2
ω is equal to ₁ . That is, since the main deflection plane G when the sub-deflection rotation angle ω ₂ is a plane, in the present invention,
The scanning lens 3 is appropriately rotated in synchronization with the sub-deflection so that the main deflection plane G and the optical axis g of the scanning lens 3 are always parallel. Moreover, the scanning lens 3 is appropriately moved in synchronization with the sub-deflection so that the intersection point P ₀ between the optical axis g and the scanning surface 4 is always located at the focal point of the scanning lens 3.

Under the above conditions, the main scanning line is always a straight line, and the coordinates (x',
y′) is expressed as follows.

x′=F ₁ (θ ₁ ) (1) y′=F ₂ (θ ₂ ) (2) Here, θ ₁ and θ ₂ are the main deflection angle and the sub deflection angle, respectively, and in the case of Fig. 3, are θ ₁ =2ω ₁ (3) θ ₂ =ω ₂ (4). Furthermore, F ₁ (θ ₁ ) is a distortion characteristic function of the scanning lens 3 due to the main deflection characteristic, and F ₂ (θ ₂ ) is a function expressing the rotation characteristic of the scanning lens 3 due to the sub-deflection characteristic. By easily realizing various characteristics using optical and mechanical means, the main scanning line is made straight on the scanning plane and no distortion occurs in the sub-deflection direction, thereby eliminating the distortion shown in the second figure. Get no scanned figure.

Next, a basic form for performing main scanning and sub-scanning at a constant speed in the present invention will be described.

Regarding the main deflection, the degree of freedom can be given to either the drive system or the distortion characteristics of the scanning lens, and by setting one of the characteristics, the other is determined.

First, the drive system for main deflection performs constant angular velocity deflection, and the main deflection rotation angle ω ₁ is proportional to time t as follows: ω ₁ = K ₁ t (5) (K ₁ = constant) Consider the case where the settings are as follows. In this case, θ ₁ =2ω ₁ =2K ₁ t from equation (3), so if the distortion characteristics of the scanning lens are set as F ₁ (θ ₁ )=fθ ₁ (6) in equation (1), then ( 1) Differentiate the equation with respect to time, dx'/dt=dF ₁ (θ ₁ )/dt=fdθ ₁ /d
t=2K ₁ f=constant(6)′. That is, the main deflection scanning speed dx'/dt is constant.

Second, the drive system for main deflection performs sinusoidal oscillating deflection, and the main deflection rotation angle ω ₁ changes over time t as follows: ω ₁ =φ ₁ sinT ₁ t (7) (T ₁ = constant) On the other hand, when the scanning lens is set to vibrate in a sinusoidal wave with an amplitude of ₁ , the distortion characteristic function F ₁ (θ ₁ ) of the scanning lens is defined as F ₁ (θ ₁ )=2φ ₁ fsin ^-1 (θ ₁ / 2φ ₁ )(8), the main deflection scanning speed becomes constant.
That is, dx'/dt=dF ₁ (θ ₁ )/dθ ₁・dθ ₁ /d
t = 2dF ₁ (θ ₁ )/dθ ₁ ·dω ₁ /dt = φ ₁ T ₁ f=constant (9), and it can be seen that the main deflection scanning speed is constant.

In the above, we have described the case where the scanning lens is given distortion characteristics so as to achieve uniform velocity scanning on the scanning plane by setting a drive system with characteristics of constant angular velocity deflection or sinusoidal vibration deflection. , an example will be described in which the main scanning speed is kept constant by imposing special deflection characteristics on the main deflection drive system without giving any particular distortion characteristics to the scanning lens.
In this case, the lens without distortion, that is, its distortion characteristic function is F ₁ (θ ₁ ) = ftanθ ₁ , and the principal deflection rotation characteristic is ω ₁ = 1/2tan ^-1 (k ₁ t) (10) By setting the drive system to do this, the main scanning speed can be kept constant. That is, dx'/dt=dF ₁ /dθ ₁・dθ ₁ /dt=2・
dF/dθ ₁ ·dω ₁ /dt = fk ₁ = constant (11), and the main scanning speed is also constant in this case.

Next, the sub-deflection will be described.

First of all, the sub-deflection drive system is set so that the sub-deflection rotation characteristic is proportional to time t, such as ω ₂ =K ₂ ·t (12) (K ₂ = constant), and the optical axis of the scanning lens 3 is By rotating g by the same amount as the sub-deflection angle θ ₂ =ω ₂ =K ₂・t, the optical axis g and Z
The distance L (θ
₂ ) as L(θ ₂ )=C ₁・θ ₂ /tanθ ₂ (13) (C ₁ : constant), and the principal point position coordinates of the scanning lens 3 (Y _L ,
_{The scanning surface 4 is _ _ _} The sub-scanning speed on the top can be kept constant. Note that Z _L is the distance from the 0'' point on the Z axis, and Y _L is the distance from the Z axis in the Y axis direction. In other words, the optical axis g of the scanning lens 3 is set as Tilt by the same angle as the deflection angle,
Further, if the lens 3 is rotated so that the principal point of the scanning lens 3 coincides with the position shown by equations (14) and (15), the focal point of the lens 3 will be included in the scanning plane 4. Then, from Fig. 3, the sub-deflection position y' is y'=L(θ ₂ )tanθ ₂ (16), so by substituting equation (13) into equation (16), y'= C ₁・θ ₂ =C ₁・ω ₂ =C ₁・K ₂・t. That is, the sub-deflection speed dy'/dt is dy'/dt=C ₁ ·K ₂ = constant (17).

Second, the secondary deflection rotation characteristic is made to oscillate sinusoidally with amplitude φ ₂ against time t, as shown in ω ₂ = φ ₂・sinT ₂・t (18) (φ ₂ = constant, T ₂ = constant). When the drive system is set, as in the first case, the optical axis g and Z axis of the scanning lens 3 are aligned using the sub-deflection angle expressed by θ ₂ =ω ₂ =φ ₂ sinT ₂・t. The distance L (θ ₂ ) between the point where these intersect and the scanning plane 4 is and the principal point position coordinates of the scanning lens 3 (Y _L ,
By rotating Z _L ) to the positions expressed by equations (14) and (15), the sub-scanning speed on the scanning surface 4 can be made constant.

Third, a case will be described in which the point where the optical axis g of the scanning lens 3 intersects with the Z axis is fixed. In this case, the drive system is adjusted so that the rotation angle ω ₂ is expressed as the sub-deflection rotation characteristic as follows: ω ₂ = tan ^-1 (k ₂・t/C ₃ ) (20) (k ₂ = constant, C ₃ = constant) By setting , the sub-scanning speed can be kept constant.

That is, from Figure 3, y′=C ₃・tanθ ₂ =C ₃・tanω ₂ (21), so by substituting equation (20) into equation (21), we get y′=k ₂・t. , dy'/dt=k ₂ = constant (22). That is, in this case as well, the sub-scanning speed is constant.

In any of the above sub-deflection cases, the rotational characteristic of the scanning lens 3 due to the sub-deflection characteristic F ₂ (θ ₂ ) in equation (2) is: F ₂ (θ ₂ )=L (θ ₂ )・tan θ It is clear from Figure 3 that it is ₂ .

Figure 4a shows the constant angular velocity main deflection rotation angle ω ₁ (based on equation (5)) with respect to time t when performing constant angular velocity main deflection using an fθ lens, and Figure 4b shows the constant velocity for the constant angular velocity main deflection. The distortion characteristics (based on equation (6)) with respect to the main deflection angle θ ₁ of the fθ lens for obtaining scanning are shown.

Fig. 5a shows the main deflection rotation angle ω ₁ (based on formula (7)) that oscillates sinusoidally with respect to time t, and Fig. 5b shows the main deflection of the arcsine lens to obtain constant speed scanning for the main deflection that sine oscillates. Distortion characteristics for angle θ ₁ ((8)
(based on the formula).

Figure 6a shows the main deflection rotation angle ω ₁ (based on formula (10)) for performing constant speed scanning using a general distortion-free scanning lens (tanθ lens), and Figure 6b shows the main deflection rotation angle ω 1 (based on formula (10)). The main deflection angle _θ of the scanning lens without
This shows the distortion characteristics for

When the secondary deflection characteristic is constant angular velocity deflection as expressed by equation (12), the characteristic diagram becomes exactly the same as the characteristic diagram in which ω ₁ is replaced with ω ₂ in Fig. 4a, and the corresponding rotation characteristic F ₂ ( θ ₂ ) is θ in Fig. 4b.
It is exactly the same as replacing ₁ with θ ₂ and replacing F ₁ with F ₂ .

Next, when the sub-deflection characteristic is a sinusoidal vibration deflection as expressed by equation (18), the characteristic diagram is exactly the same as the characteristic diagram in which ω ₁ is replaced with ω ₂ in Fig. 5a, and the corresponding rotation characteristic F ₂ (θ ₂ ) is shown in FIG. 5b by replacing θ ₁ and F ₁ with θ ₂ and F ₂ , respectively.

Next, when the sub-deflection characteristic is a deflection expressed by equation (20), it is shown by replacing ω ₁ with ω ₂ in Fig. 6a, and the corresponding rotation characteristic F ₂ is shown in Fig. 6b. θ ₁ and F ₁ in θ ₂ ,
It is shown by replacing F ₂ .

7a, 7b, and 7c, the distance L (θ ₂ ) between the scanning surface 4 and the point where the optical axis g of the scanning lens 3 intersects with the Z axis in FIG. 3 is expressed as the sub-deflection angle θ ₂ Fig. 7a corresponds to the case where the sub-deflection characteristic is constant angular velocity, Fig. 7b corresponds to the case where the sub-deflection characteristic is sinusoidal vibration,
FIG. 7c corresponds to the case where the sub-deflection characteristic is expressed by the arctangent function of equation (20).

Figures 8a, 8b, and 8c show how the image-side principal point position (Y _L , Z _L ) of the scanning lens changes, and Figure 8a shows the change when the sub-deflection characteristic is at constant angular velocity. FIG. 8b corresponds to the case where the sub-deflection characteristic is a sinusoidal vibration, and FIG. 8c corresponds to the case where the sub-deflection characteristic is represented by the arc tangent function of equation (20).

In the above embodiments, the main deflection rotation axis Y _M axis includes the origin 0 of the orthogonal coordinate system XYZ system based on FIG. 3, but the Y _M axis does not necessarily have the origin 0.
may not be included. For example, as shown in Fig. 9, the X-axis is used as the rotation axis for sub-deflection so that the deflection surface _M always forms an angle of 45° with the main deflection rotation axis YM, and the incident beam 1 is always parallel to the _YM axis. If so, the main deflection plane G
becomes a plane. Note that in FIG. 9, the characters marked with "'" indicate when the sub-deflection is performed by the sub-deflection rotation angle _ω2 . In this case as well, the same development as in the above-mentioned embodiment can be achieved, so a description thereof will be omitted here.

Regarding the time t described in the present invention, the origin (t=0) is set for each main scan. In other words, the function that includes time t with respect to the main deflection or the sub-deflection is 1
A time origin shall be set and defined for each deflection.

FIG. 10 shows an embodiment of the two-dimensional scanning device of the present invention. In the figure, reference numeral 101 denotes a polygonal rotating mirror, which is fixed to a rotating shaft 102a of a drive motor 102. or,
A drive motor 102 is attached to a substrate 103.
Side plates 104 and 105 are raised from the left and right ends of the board 103, and these side plates 104 and 105 are connected to the board 10.
The shafts 108 and 109 are respectively fitted onto shafts 108 and 109 provided on bearing plates 106 and 107 that protrude from the center. Note that the shaft 108 is a hollow shaft through which the light beam passes. Groove columns 110 and 111 are provided protrudingly on the front part of the substrate 103, and the lens plate 112 is fitted into the grooves 110a and 111a of the groove columns 110 and 111.
can be moved up and down. On the other hand, the scanning lens 113
is fitted onto the lens plate 112 so as to be movable back and forth.

When the drive motor 102 rotates, the rotation shaft 102a
A polygonal rotating mirror 101 fixed to rotates at a constant angular velocity in the direction of arrow a. On the other hand, the lower end of the rotating shaft 102a is connected to a gear box 114.
An electromagnetic clutch 11 is attached to the output shaft of the gearbox 114.
5 are connected to each other, and a gear 116 is coupled to the output shaft of an electromagnetic clutch 115. This gear 116 is meshed with a half-moon gear 117 fixed to the bearing plate 106 with the center of the shaft 108 as the rotation center, and when the clutch 115 is connected, the gear 116 is rotated by the rotation of the motor 102, and the half-moon gear 117 is fixed. It revolves around the outer circumference of the gear 117 at a constant speed. gear 116
The substrate 103 to which the drive motor 102 is attached and everything provided on the substrate 103 rotate about the shafts 108 and 109 as the rotation center revolves around the shaft 108 .

A gear 154 is fixed to the right bearing plate 104 with the center of the shaft 108 as the center of its circumference. On the other hand, the gears 118 and 119 mesh with the gear 154 with the same number of teeth and are sequentially interlocked with each other so that the respective rotating shafts 1
It is attached to the right side plate 104 by 18a and 119a. Therefore, when the substrate 103 rotates by θ degrees, the gear 119 also rotates by θ degrees. The vertically moving cam disc 120 is connected to the gear 119 by its rotation shaft 119a.
Fix it coaxially with. The driven rod 121 is installed on the lens plate 112, and this driven rod 121 is attached to the groove plate 110.
The cam disk 120 is always brought into contact with the cam disk 120 by the tensile force of the spring 122 through the elongated hole 110b provided in the cam disk 120. Therefore, when the gear 119 rotates, the cam disk 120 rotates, and the lens plate 112 is moved in the direction of the arrow b in conjunction with the driven rod 121 that is provided on the outer periphery of the cam disk 120 and follows the change in the cam diameter. Move to. Therefore, the scanning lens 113 fitted on the lens plate 112 also moves and changes in the same way.
That is, the movement direction in the direction of arrow b and the light deflection surface 10
It is set parallel to 1a.

Here, the cam diameter characteristics of the above-mentioned vertically movable cam disk 120 will be explained based on FIGS. 11a and 11b. 11a and 11b show the case where the sub-deflection rotation characteristic, that is, the rotation characteristic of the substrate 103 shown in FIG. 10, is set to θ ₂ =K·t (K=constant).

First, the shape of the vertically movable cam disk 120 is determined as follows. In Fig. 3, the secondary deflection angle θ ₂
Then, since the distance between the axis h and the optical axis g is the amount of vertical movement of the scanning lens 3, if that amount is Δh, then
Δh is expressed as Δh=−(L ₀ −L(θ ₂ )) sin θ ₂ . Gear 11 that rotates the vertically moving cam disk 120 from the rotating gear 117' of the base plate 103
If the gear ratio up to 9 is γ _h , the vertical moving cam 1
For a rotation angle γ _h θ ₂ of 20, the vector radius γ of the cam 120 shown in FIG. 11b is expressed as γ=γ ₀ +Δh. However, γ ₀ is the radius vector of the cam 120 when θ ₂ =0, that is, no sub-deflection is performed. FIG. 11a depicts how the vector radius γ changes with respect to the rotation angle γ _h θ ₂ of the cam 120. L(θ ₂ ) in this case is given by equation (13). Further, L ₀ is the distance from the scanning plane 4 to the deflection reference point 0.

The vertically moving cam disk when the rotation angle characteristic of the sub-deflection is set to cause sinusoidal vibration with amplitude φ with respect to time t, as shown in θ=φsinT・t (φ=constant, T=constant). 1
The shape of 20 can also be determined in the same manner as described above. That is, the vertically moving cam disk 12
The vertical movement amount Δh of 0 is expressed as Δh=-(L ₀ -L(θ ₂ )) sin θ ₂ , so according to this movement amount Δh, the radius vector γ of the cam 120 is expressed as γ=γ ₀ +Δh Just set it. However, in this case, L(θ
₂ ) is given by equation (19).

Referring again to FIG. 10, the shaft 1 is mounted on the bearing plate 107.
A gear 123 is fixed with the center of 09 as the center of the circumference. On the other hand, gears 124 and 125 are
They are attached to the left side plate 105 by rotating shafts 124a and 125a, respectively, so that they mesh with each other with the same number of teeth and are sequentially interlocked with each other. Therefore, when the substrate 103 rotates by θ degrees, the gear 125 also rotates by θ degrees. A back-and-forth moving cam disk 126 is fixed to the gear 125 coaxially with its rotating shaft 125a. A driven member 127 is mounted on the scanning lens 113, and the driven member 127 is always brought into contact with the cam 126 by the tension of a spring 128. Therefore, when the gear 125 rotates, the cam disk 126 rotates, and the scanning lens 113 moves in the direction of arrow c in conjunction with the driven member 127 that follows the change in the outer circumference of the cam disk 126, that is, the cam diameter. do.

Here, the cam diameter characteristics of the longitudinally movable cam disk 126 will be explained based on FIGS. 12a and 12b.

12a and 12b show the case where the sub-deflection rotation characteristic, that is, the rotation characteristic of the substrate 103 shown in FIG. 10, is set to θ ₂ =K·t (K=constant).

The shape of the cam disk 126 for focusing is set as follows. From Figure 3, first, lens 3.
The amount of movement Δl in the optical axis direction is Δl=L( _cosθ2-1 )+L( _θ2 )
・(secθ ₂ −cosθ ₂ ) Therefore, the radius vector l of the cam disk 126 is expressed as l=l ₀ +Δl. FIG. 12b shows the radius vector l for the rotation angle ε _l θ ₂ of the cam disk 126, where ε _l is the gear ratio from the rotating gear 123 of the base plate 103 to the rotating gear 125 of the cam 126. It is.

FIG. 12a illustrates the change in radius l of the cam 126 with respect to its rotation angle ε _l θ ₂ .
However, L(θ ₂ ) in the expansion formula for the movement amount Δl mentioned above
is given by equation (13).

When the sub-deflection rotation characteristic is sinusoidal vibration with amplitude φ with respect to time t, such as θ=φsin(T・t) (φ=constant, T=constant), the characteristics of the focusing cam 126 are as follows.
Similarly to the case of the cam 120, the amount of movement Δl in the optical axis direction is Δl=L(cosθ ₂ -1)+L(θ ₂ )
Since it is given by (secθ ₂ -cosθ ₂ ), by using this movement amount Δl, l=l ₀ +Δl is obtained as the vector radius l. However, L(θ ₂ ) in this case is given by equation (19). In addition, l ₀ in the formula representing the radius vector l is the cam 126 when the sub-deflection is not performed.
Let be the vector radius of

Again, in FIG. 10, a pin member 129 is installed on the right bearing plate 106, and a spring 131 is stretched between this pin member 129 and a pin member 130 installed on the gearbox 114. When the gear 116 continues to rotate in the direction of the arrow d against the force of the spring 131 and the pin member 130 comes into contact with the tongue 132a of the switch, for example the micro switch 132, the switch 132 generates a scan completion signal. In response to the scan completion signal, the electromagnetic clutch 115 operates and the rotational drive transmission of the motor 102 to the gear 116 is cut off, so that the gear 116 can freely rotate, and the compression force of the spring 131 causes the pin member 130 to be rotated. is arrow d
The substrate 103 is pulled in the opposite direction, and therefore the substrate 103 also rapidly rotates counterclockwise. During the rotation of the pin member 130 by the spring 131, the pin member 130 contacts the switch 133, and at the same time the counterclockwise rotation of the substrate 103 is stopped, the switch 133 generates a scan start preparation completion signal.

A knife edge 13 is attached to the tips of rod members 134 and 135 that extend from the substrate 103 to the vicinity of the scanning surface 140.
Photodetectors 138 and 139 equipped with lenses 6 and 137 are arranged so that the beam light emitted from the scanning lens 113 is incident thereon. A photodetector 142 is suitably disposed on arm 141 between rod members 134 and 135 such that photodetector 142 detects the scanning beam reflected from scanning surface 140. Note that scanning plane 1
40 is attached to a holder 143. A laser oscillator 145 and an optical modulator 1 are mounted on the optical stage 144.
46, a mirror adjuster 147, and a beam expander lens 148 are mounted.

A laser beam 149 emitted from a laser oscillator 145 enters an optical modulator 146 . The modulated laser beam 150 is reflected by a mirror 147 and further passes through a beam ex-pander lens 148.
The beam diameter is expanded by this, and the beam is incident on one deflection surface 101a of the polygonal reflecting mirror 101. The beam 151 incident on the deflection surface 101a is
is deflected by the rotation of a, and its deflected beam 152
main scans the object to be scanned, that is, the scanning surface 140, in the X→X' direction through the scanning lens 113.
Since the scanning beam 153 is incident on the photodetector 138 before the scanning beam 153 is incident on the scanned object surface 140, the photodetector 138 generates an initial position detection signal of the scanning beam 153. scanning beam 153
enters the photodetector 139 after passing through the scanned object surface 140, so the photodetector 139 generates a one-line scanning end signal. By setting the scanning beam 153 to be a constant level intensity beam that is not modulated, the photodetector 142 that receives the reflected light reflected from the surface 140 of the object to be scanned has a certain level of intensity.
Image information about the image is generated.

As described above, in the present invention, the polygonal rotating mirror 101
is the laser beam 1 in conjunction with the rotation of the motor 102.
The main scanning is repeated by deflecting the motor 49 in the direction of
By rotating the substrate 103 in conjunction with the rotation of the laser beam 149, the laser beam 149 is also deflected in the Y→Y' direction on the scanned object surface 140 to perform sub-scanning.

In the above example, the case of reading a two-dimensional figure using a laser beam has been described, but by applying an appropriate modulation input to the optical modulator 146, a two-dimensional figure can be correspondingly written on the scanning surface 140. Of course, it can also be done.

Next, another embodiment of the two-dimensional scanning device of the present invention will be described.
Shown in Figure 3. Reference numeral 201 in the figure denotes a mirror for main deflection, which is rotatably attached to the bottom plate 202. The rotational axis k-k' of the mirror 201 is orthogonal to the sub-deflection rotational axis j-j', and its relative position always remains unchanged. Further, its main deflection rotation characteristic is expressed by the following equation, and it rotates as indicated by arrow g.

ω ₁ = C ₄ tan ^-1 (C ₅ t) However, ω ₁ : Rotation angle of mirror 201 C ₄ , C ₅ : Constant, t : Time The scanning lens 203 is a general distortion-free lens, and its optical axis is always It coincides with the main deflection plane, and its lens barrel is fixed to arms 204a and 204b. Arms 204a, 204b are grooved plates 205a, 2
05b to allow smooth sliding in the groove formed in the h direction. In addition, armrests 204a and 204
There is a guide roller 206 that rotates freely at the tip of b.
Attach a and 206b. These guide rollers 206a and 206b are compressed by compression springs 208a and 20
8b guide rails 207a and 207b
It rolls on the inner surfaces of the guide rails 207a and 207b as shown by arrow i while being constantly pressed against it.
The length l of the arms 204a and 204b is determined by the focal length of the scanning lens 203.
Rollers 206a and 206b at the tips of a and 204b
The plane created by the line connecting the rotation center axes of is the scanning plane
Always matches XY. Groove plates 205a and 205b
are fixed to side plates 209a and 209b, respectively. The side plates 209a and 209b are bearings 210
a and the support member 211 via the hollow bearing 210b.
a and 211b, and freely rotates about the sub-deflection rotation axis j-j' as the rotation axis. Further, both the side plates 209a and 209b are connected by a cam follower shaft 212, and the cam follower shaft 2
A cam follower 213 is fitted into the cam 12 in a freely rotatable state so that the cam follower 213 is always in contact with the cam surface of the cam 214. This cam 214 is attached to the shaft of a drive motor 215,
The cam 214 rotates at a constant angular velocity as shown by arrow e.
Cam characteristics of this cam 214 and cam follower 21
3, the bearings 210a and 210
The scanning lens body, which is held by support members 211a and 211b, rotates as shown by arrow f with the j-j' axis as the rotation axis to perform sub-deflection. The sub-deflection rotation characteristic is expressed by the following equation.

ω ₂ = tan ^- ₁ (k ₂ t/L) where ω: rotation angle of the main body with respect to the j-j' axis k ₂ : constant L: distance between the sub-deflection rotation axis and the scanning plane XY t = time Based on the above formula When the main body rotates, the guide rollers 206a and 206b move toward the guide rail 207.
It rolls on the pressing surfaces of a and 207b. At the same time, the arms 204a and 204b are extended or pushed back from the groove plates 205a and 205b to perform reciprocating motion. The scanning lens 203, which is integrated with the armrests 204a and 204b, similarly reciprocates,
As a result, the focus of the scan lens 203 is always on the scan plane.
Connected on XY. Further, in this example, since the sub-deflection rotation is performed by the cam 214, there is also an advantage that quick return of the sub-deflection is easy.

A laser oscillator 217, an optical modulator 218, a mirror adjuster 219, and a beam expander lens 220 are mounted on an optical stage 216. A laser beam 221 emitted from a laser oscillator 217 enters a modulator 218, and a laser beam 222 modulated here is reflected by a mirror 219, and the beam diameter is further expanded by a beam expander lens 220, and the beam diameter is expanded by a hollow bearing 210b. The light enters the above-mentioned main deflection mirror 201 through the sub-deflection rotation axis j-j' in the hollow part. The beam 223 incident on the mirror 201 is deflected by the rotation g of the mirror 201, and the deflected beam 230 passes through the scanning lens 203 and scans in the XX' direction on the scanning plane. A semi-transparent mirror 225 and a knife edge 2 are mounted on the bridging member 224 whose both ends are fixed to the arms 204a and 204b.
26, a photodetector 227 is provided, and a knife edge 228 and a photodetector 229 are further provided on the guide rail 207a. The semi-transparent mirror 225, the knife edge 226, and the photodetector 227 are the main deflection mirror 201.
Among the beams 230 deflected by the beam 230, a beam having a certain deflection angle is detected and a main scanning cueing signal is generated. Also, Knife Tsuji 228
Then, the photodetector 229 detects the beam transmitted through the semi-transparent mirror 225 when the rotation angle of the sub-deflection reaches a certain fixed angle, and generates a cue signal for sub-scanning.

As is clear from the above, according to the present invention, the scanning lens has distortion characteristics corresponding to the characteristics of the main scanning deflection, and by rotating such a scanning lens in accordance with the characteristics of the sub deflection, Since directional distortion can be eliminated and scanning speeds in both main scanning and sub-scanning can be made constant, distortion-free scanned figures can be obtained. Therefore, distortion-free two-dimensional scanning can be achieved with a relatively simple optical and mechanical configuration, without the need to correct the distortion of the scanning figure using complicated electrical signal processing means as in the past. can.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a distorted figure produced by a conventional two-dimensional scanning device, Fig. 2 is a diagram showing an example of a distortion-free figure produced by the present invention, and Fig. 3 is a diagram showing the principle of the two-dimensional scanning device of the present invention. Diagrams for explaining the configuration, Figures 4a, 5a, and 6a, respectively show the case of main deflection with constant angular velocity using an fθ lens, the case of main deflection with sine vibration, and the case of main deflection with constant angular velocity using a tanθ lens. The characteristic curve diagrams, Figures 4b, 5b, and 6b, which show the relationship between the time t and the main deflection rotation angle ω ₁ when performing deflection, are the same as those in Figures 4a, 5a, and 6a, respectively. Corresponding to the case, the characteristic curve diagrams 7a, 7b, and 7c show the relationship with respect to the main deflection angle θ ₁ of each scanning lens for performing main scanning at a constant speed. (θ ₂ ) with respect to the sub-deflection angle θ ₂ when the sub-deflection characteristics are equiangular deflection, sinusoidal deflection and arctangent deflection, respectively, and Figs. 8a, 8b and 8c are the same. Characteristic curve diagrams showing how the image-side principal point positions Y _L and Z _L of the scanning lens change in the three cases described above, FIG. 9 is a diagram showing a modification of the two-dimensional scanning device of the present invention, and FIG. 10 and FIG. 13 are perspective views showing two specific examples of the two-dimensional scanning device of the present invention, and FIG.
Figures a and 11b are a characteristic diagram and an explanatory diagram of the vertically moving cam, respectively, and Figures 12a and 12b are a cam characteristic diagram and an explanatory diagram of the longitudinally movable cam, respectively. DESCRIPTION OF SYMBOLS 1...Incoming parallel beam, 2...Two-dimensional deflection mirror, 3...Scanning lens, 4...Scanning surface, 100...
... Bottom plate, 101 ... Multifaceted rotating mirror, 101a ... Light deflection surface, 102 ... Drive motor, 102a ... Rotating shaft, 103 ... Substrate, 104, 105 ... Side plate, 106, 107 ... Bearing plate, 108 ,109
...Axis, 110, 111...Groove column, 110a, 1
11a...Groove, 110b...Elongated hole, 112...Lens plate, 113...Scanning lens, 114...Gearbox, 115...Electromagnetic clutch, 116,1
18, 119, 154... Gear, 117... Half moon gear, 118a, 119a... Rotating shaft, 120...
... Vertical moving cam disk, 121 ... Follower rod, 122
...Spring, 123,124,125...Gear, 1
24a, 125a...rotating shaft, 126...back and forth moving cam disc, 127...driven member, 128...spring, 129, 130...pin member, 131...spring, 132...switch, 132a...switch Tongue piece, 133... switch, 134, 135...
Rod member, 136, 137...knife edge, 13
8,139...Photodetector, 140...Scanning plane, 1
41...Arm, 142...Photodetector, 143...Holder, 144...Optical stage, 145...Laser oscillator, 146...Optical modulator, 147...Mirror adjuster, 148...Beam expander Lens, 149... Laser beam, 150... Modulated laser beam, 151... Incident beam, 152...
Deflected beam, 153... Scanning beam, 201...
Main deflection mirror, 202...bottom plate, 203...scanning lens, 204a, 204b...branch, 205
a, 205b...Groove plate, 206a, 206b...
Guide roller, 207a, 207b... Guide rail, 208a, 208b... Compression spring, 209
a, 209b... side plate, 210a, 210b...
Hollow bearing, 211a, 211b...support member, 2
12... Cam follower shaft, 213... Cam follower, 214... Cam, 215... Drive motor, 216... Optical mounting stand, 217... Laser oscillator, 218... Optical modulator, 219... Mirror adjuster, 220 ...beam expander lens,
221...Laser beam, 222...Laser beam, 223...Incoming beam, 224...Bridging member, 225...Semi-transparent mirror, 226, 228...Knife edge, 227...Photodetector, 229...Photodetection vessel.

Claims (1)

[Claims] 1. It has a mirror surface that two-dimensionally deflects incident light, a main deflection rotation axis is determined so that the relative positional relationship with the mirror surface remains unchanged, and an axis parallel to the main deflection rotation axis. A two-dimensional deflector, wherein a sub-deflection rotation axis is set orthogonal to or perpendicular to the main deflection rotation axis, and the incident light is made incident on the mirror surface parallel to or on the sub-deflection rotation axis. and a scanning lens disposed between the two-dimensional deflector and the scanning surface to receive the polarized light from the two-dimensional deflector and emit the scanning light toward the scanning surface, The main deflection plane formed by the beam deflected by the mirror by the main deflection rotation is made parallel to the optical axis of the scanning lens, and the scanning lens is rotated in synchronization with the sub-deflection rotation of the two-dimensional deflector. A two-dimensional scanning device characterized in that the focal point of the scanning lens is always included within the scanning plane, and the main scanning speed and sub-scanning velocity of the scanning beam on the scanning plane are respectively constant. 2. In the device according to claim 1,
A two-dimensional scanning device, characterized in that the scanning lens has a distortion characteristic corresponding to the main deflection rotation characteristic of the two-dimensional deflector, so that the main scanning speed on the scanning surface is constant. 3. In the device according to claim 1,
A two-dimensional scanning device, comprising means for rotating the scanning lens by an angle whose optical axis is the same as a sub-deflection angle of the two-dimensional deflector. 4. In the device according to claim 2,
The main deflection rotation characteristic of the two-dimensional deflector is a constant angular velocity deflection characteristic, and the distortion characteristic of the scanning lens is F ₁
A two-dimensional scanning device characterized in that (θ ₁ ) is set as F ₁ (θ ₁ )=fθ ₁ (f: focal length of a scanning lens, θ ₁ : main deflection angle). 5. In the device according to claim 2,
The main deflection rotation characteristic of the two-dimensional deflector is a sinusoidal vibration deflection characteristic, and the distortion characteristic of the scanning lens is F ₁
(θ ₁ ), F ₁ (θ ₁ )=2fφ ₁ sin ^-1 (θ ₁ /2φ ₁ )
(f: focal length of scanning lens, θ ₁ : principal deflection angle, φ ₁ :
A two-dimensional scanning device characterized in that the amplitude of sine vibration) is made. 6. In the device according to claim 2,
The rotation angle ω ₁ of the main deflection of the two-dimensional deflector is ω ₁ =
The main deflection drive means is determined to be expressed as 1/2 tan ^-1 (k ₁ ·t) (where k ₁ is a constant, t is time), and the distortion characteristic F ₁ (θ ₁ ) of the scanning lens is defined as: F ₁ (θ
₁ )=f・tanθ ₁ (f: focal length of scanning lens,
A two-dimensional scanning device characterized in that θ ₁ :main deflection angle). 7. In the device according to claim 3,
The secondary deflection rotation characteristic of the two-dimensional deflector is a constant angular velocity deflection characteristic, and the distance L between the intersection of the optical axis of the scanning lens and the deflection reference axis of the two-dimensional deflector and the main scanning deflection surface. A two-dimensional scanning device characterized in that (θ ₂ ) is set as L(θ ₂ )=C ₁ ·θ ₂ /tanθ ₂ (C ₁ : constant). 8. In the device according to claim 3,
The secondary deflection rotation characteristic of the two-dimensional deflector is a sinusoidal oscillation deflection characteristic with an amplitude φ ₂ , and the intersection of the optical axis of the scanning lens and the deflection reference axis of the two-dimensional deflector and the main scanning deflection surface is The distance L (θ ₂ ) between A two-dimensional scanning device characterized by the following. 9. In the device according to claim 3,
The rotation angle ω ₂ of the sub-deflection of the two-dimensional deflector is expressed as ω ₂ = tan (k ₂・t/C ₃ ) (k ₂ , C ₃ : constant, t:
time), and the distance L (θ ₂ ) between the intersection of the optical axis of the scanning lens and the deflection reference axis of the two-dimensional deflector and the main scanning deflection surface is set to a constant value L. A two-dimensional scanning device. 10 In the apparatus according to claim 3, the image-side principal point position (Y _L , Z _L ) of the scanning lens
(However, Z _L is the distance from the intersection on the deflection reference axis Z, and Y _L is the distance from the deflection reference axis Z on the plane containing the deflection reference axis Z and the main deflection rotation axis.) The scanning lens is provided with means for rotating the scanning lens so that it is at a position expressed by Y _L =L(θ ₂ )・tan _{θ 2} −f・sin θ _{2 Z L =} L(θ ₂ )−f・cos θ 2 Features: Two-dimensional scanning device. 11. The apparatus according to claim 1, further comprising a photodetector for detecting the position of the scanning beam, and the photodetector is synchronized with a sub-scanning operation that rotates about the sub-deflection rotation axis. A two-dimensional scanning device characterized in that the scanning device is configured to be rotated. 12. The apparatus according to claim 1, further comprising a photodetector that receives reflected light from the scanning surface of the scanning beam, and the photodetector is rotated about the sub-deflection rotation axis. A two-dimensional scanning device characterized in that it is rotated in synchronization with a sub-scanning operation.